A single wafer type liquid processing apparatus has been used in a semiconductor device manufacturing process. The liquid processing apparatus holds a substrate, i.e., a semiconductor wafer (“wafer”) horizontally and supplies various chemical liquids to the peripheral edge of the wafer while rotating the wafer about a vertical axis, thereby removing, for example, a resist film, pollutant, or an oxidation film attached to the peripheral edge of the wafer.
As an example, Japanese Laid-Open Publication No. 2007-142007 discloses a technology of etching a film of the peripheral edge of a substrate (paragraphs [0033] to [0036] and [0057], and FIG. 8A). The technology arranges a disc-shaped shielding plate to be opposed to a substrate to be processed so as to shield the substrate from the external atmosphere, and supplies a chemical liquid toward the substrate from a peripheral edge processing nozzle installed on the peripheral edge of the shielding plate while the substrate is being rotated, thereby etching a thin film at the peripheral edge of the substrate. However, Japanese Laid-Open Publication No. 2007-142007 does not disclose a technology of confirming whether the chemical liquid supplied from the peripheral edge processing nozzle is supplied to a desired position on the peripheral edge of the substrate or not.